As a few others have posted, Wifi+Cellular only makes sense if you will use it. For us, we live in Southeast Palm Beach County, deal with hurricanes and thunderstorms frequently so having the ability to connect via cell has proven to be quite useful. I’d add - our Internet Provider (Xfinitiy/Comcast) is extraordinarily unreliable and cannot tell you how many times a day they drop out for periods of 1 or 2 hours while I am on work calls. Simply switching to cell and continuing to function has been a lifesaver more than I can count.
Never mind traveling, security concerns about some public wifi, etc. Have had Cell since the very first iPad with ATT Unlimited Data and have used it through an iPad Mini, then my current 2020 11” Pro. I’m getting the 12.9 Wifi+Cell and my wife gets the 11” - she has stopped using our iMac for bills, browsing, creation, etc. and borrows the iPad Pro. She is an artist and the pencil has been a delight. So the 11” goes to her and I will get the 12.9 as these old eyes want the bigger screen ... and I actually do multitask and the bigger real estate will work.
My biggest wish is actually an iPad OS addition and an old one...one multiple profiles/login for iPad. This way my wife and I could switch between devices as needed...i.e. when riding my bike to the beach for a business meeting, I prefer the smaller 11”. Doubt will see that so need to buy a slightly larger sling bag for the 12.9” now.
As for 2020 vs. 2021...honestly there is no single feature that I think is a huge compelling difference that would drive anyone to buy a 2021. As a group of features, the 2021 future proofs the device and as a matter of practice, I always get the latest at time of purchase and have never regretted. If they store the Apple Pencil in the new keyboard that will be a big win
small I know but one I would definitely appreciate.